OMF000502 Network Planning Principle ISSUE1.3

OMF000502 Network Planning Principle ISSUE1.3

OMF000502 Network Planning Principle ISSUE1.3

Wireless Training Department

Introduction to GSM network

Mobile radio link

Network planning procedure

Advanced network planning

Course ContentsCourse Contents

Introduction to GSM NetworkIntroduction to GSM Network

1. GSM system architecture

2. GSM bandwidth

3. Difference between GSM900 and GSM1800

4. GSM Logical channels

GSM System ArchitectureGSM System Architecture

Other MSC

Other BTS´s

VLR HLREIR

AuCOMC

GSM BandwidthGSM Bandwidth

GSM 900 :

Channel spacing 200kHz

GSM 1800 :

Channel spacing 200kHz

1710 1785 1805 1880

Duplex Spacing : 95 MHz

890 915 935 960

Duplex Spacing : 45 MHz

Difference Between GSM900 and GSM1800Difference Between GSM900 and GSM1800

GSM900 and GSM1800 are similar

GSM 900 GSM 1800

Frequency band 890...960 MHz 1710...1880 MHz

Number of channels 124 374

Channel spacing 200 kHz 200 kHz

Access technique TDMA TDMA

Mobile power 0.8 / 2 / 5 W 0.25 / 1 W

There are no major differences between GSM 900 and GSM 1800

There are no major differences between GSM 900 and GSM 1800

Logical ChannelsLogical Channels

GSM900/GSM1800 logic channel architecture

Broadcast ControlChannel (BCCH)

Control ChannelsCommon ControlChannel (CCCH)

Traffic Channels (TCH)

FCH SCH BCCH(Sys Info)

TCH/FAGCH RACH SDCCH FACCH

SACCH

TCH/H

TCH/9.6FTCH/ 4.8F, HTCH/ 2.4F, H

PCH

Common Channels (CCH)

Dedicated Channels (DCH)

Logical Channels

Downlink ChannelsDownlink Channels

FCCH

SCH

BCCH

PCH

AGCH

BCCH

CCCH

Common Channels

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated Channels

Uplink ChannelsUplink Channels

RACH CCCHCommon Channels

SDCCH

SACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated Channels

Use of Logical Channels Use of Logical Channels

Search for frequency correction burst

Search for synchronization sequence

Read system information

Listen paging message

Send access burst

Wait for signaling channel allocation

Call setup

Assign traffic channel

Conversation

Call release

FCCH

SCH

BCCH

PCH

RACH

AGCH

SDCCH

SDCCH

TCH

FACCH

idle mode

“off” state

dedicated mode

idle mode

Logical Channels MappingLogical Channels Mapping

Logical channels are mapped to physical channels

Signaling : sequences of 51 frames

Traffic : sequences of 26 frames

For combined BCCH

CCCH blocks can be either PCH or AGCH

Some blocks may be configured as SDCCH

R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R

F S B B B B C C C C S C C C C C C C CF S C C C C C C C CF S C C C C C C C CF S C C C C C C C CF -

51 TDMA frames ~ 235,4 msecBCCH + CCCH (uplink)

BCCH + CCCH (downlink)

Exercises

1. Write down the frequency used for uplink and downlink.

Answer: GSM system uses different frequency for uplink and

downlink.

GSM900:

Uplink: 935---960 Downlink: 890---915

GSM1800:

Uplink: 1805--1880 Downlink: 1710--1785

Exercises

2. Write down the types of logical channels and the hierarchy

Answer:

Broadcast ControlChannel (BCCH)

Control ChannelsCommon ControlChannel (CCCH)

Traffic Channels (TCH)

FCH SCH BCCH(Sys Info)

TCH/FAGCH RACH SDCCH FACCH

SACCH

TCH/H

TCH/9.6FTCH/ 4.8F, HTCH/ 2.4F, H

PCH

Common Channels (CCH)

Dedicated Channels (DCH)

Logical Channels



Mobile radio link



Mobile Radio LinkMobile Radio Link

1. Radio wave propagation

2. Propagation models

3. Antenna systems

4. Diversity technique

5. Interference and interference reduction

6. Link budget

Radio Link PropagationRadio Link Propagation

Multi-path propagation

Radio path is a complicated propagation medium

Limited transmitting energy

The service range is determined by the transmission power of

mobiles

Battery life-time

Limited spectrum

Set upper limitation for data rate (Shannon´s theorem)

Additional effort needed for channel coding

Frequency reused result in self- interference

Radio Propagation EnvironmentRadio Propagation Environment

Multi-path propagation

Shadowing

Terrain

Building

Reflection

Interference

ReflectionsReflections

Strong echoes can cause excessive transmission delay

No impact If the delay falls in the equalizer window

Cause self-interference if the delay falls out of the equalizer

window

direct signalstrong reflected signal

equalizer window 16 s

amplitude

delay time

long echoes, out of equalizer window:self-interference

Fading(1)Fading(1)

Slow fading (Lognormal Fading) Shadowing due to large obstacles o

n propagation direction

Fast fading (Rayleigh fading) Serious interference from multi-path

signals

+10

0

-10

-20

-300 1 2 3 4 5 m

Level (dB)

920 MHzv = 20 km/h

Fading(2)Fading(2)

time

power

2 sec 4 sec 6 sec

+20 dB

mean value

- 20 dB

lognormal fading

Rayleighfading

Signal VariationsSignal Variations

Rayleigh fading

Lognormal fading

Large scale variation

Cause Superposition of multiple propagation paths with different phase

Shadowing or reflection by cars, trees, buildings

Prop. path profile, terrain & clutter structure, Earth curvature

Correlation < 10 ... 100m > 100m

Prediction unpredictable mostly predictable (buildings!!)

predictable (maps, terrain database)

Planning method

apply statistical thresholds for Rayleigh fading signals

consider lognormal distribution around local mean (use = 3 ... 10dB)

use maps or digital terrain & clutter databases to predict (50 ..200m pixel resolution)

PropagationPropagation

Free- space propagation

Signal strength decreases with distance increases

Reflection

Specula R.

Amplitude : A --> α*A (α< 1)

Phase : --> -Ф

Polarization : material determining phase shift

Diffuse R.

Amplitude : A --> α*A (α<< 1)

Phase : random

Polarization : random

specula reflection

diffuse reflection

D

PropagationPropagation

Absorption

Heavy amplitude attenuation

Material determining phase shift

Diffraction

Wedge-model

Knife edge

Multiple knife edges

A A - 5..30 dB




3. Antenna systems



6. Link budget

Propagation ModelPropagation Model

Historical CCIR- Model for Radio station

Not very accurate nor serious

Okumura- Hata

Empirical model

Measure and estimate additional attenuations

Applied for larger distance estimation (range: 5 .. 20km)

Not suitable for small distance ( < 1km)

Hata ModelHata Model

Model used for 900 MHz

L A B f h a h

h d Lb m

b morpho

log . log ( )

( . . log ) log

1382

44 9 655

with

f frequency in MHz

h BS antenna height [m]

a(h) function of MS antenna height

d distance between BS and MS [km] and

A= 69.55, B = 26.16 (for 150 .. 1000 MHz)

A= 46.3 , B = 33.9 (for 1000 ..2000MHz)

additional attenuation dueto land usage classes

Land Usage TypesLand Usage Types

Urban small cells, 40..50 dB/Dec attenuation

Forest heavy absorption; 30..40 dB/Dec; differs with

season (foliage loss)

Open, farmland easy, smooth propagation conditions

Water propagates very easily ==> dangerous !

Mountain surface strong reflection, long echoes

Glaciers very strong reflection; extreme delay , strong

interferences over long distance

Hilltops can be used as barriers between cells, do not

use as antenna or site location

Walfish- Ikegami ModelWalfish- Ikegami Model

Model used for urban micro-cell propagation. Assume regular

city layout (“Manhattan grid”). Total path loss consists of three

parts:

Line-of-sight loss LLOS

Roof-to-street loss LRTS

Mobile environment loss LMS

hw

b

d

Mobil Radio LinkMobil Radio Link


2. Propagation model

3. Antenna system



6. Link budget

Antenna CharacteristicsAntenna Characteristics

Lobes

Main lobes

Side and Back lobes

Front-to-Back ratio

Half-power beam-width

Antenna downtilt

Polarization

Frequency range

Antenna impedance

Mechanical size

Coupling Between AntennasCoupling Between Antennas

main lobe

5 .. 10

Horizontal separation

Sufficient decoupling distance: 5-10λ

Antenna patterns superimposed if

distance too close

Vertical separation

Decoupling distance:1λ can provide good RX /TX decoupling

Minimum coupling loss

Recommended decoupling

TX - TX: ~20dB

TX - RX: ~40dB

Horizontal decoupling distance depends on

Antenna gain

Horizontal rad. pattern

Omni-directional antenna

Use vertical separation for RX and TX

Use vertical separation (“fork”) for RX and diversity RX

Vertical decoupling is much more effective

0,2m

Omni-directional.: 5 .. 20mdirectional : 1 ... 3m

Installation ExamplesInstallation Examples

Installation ExamplesInstallation Examples

Directional antenna

Antenna downtilt

Improve hotspot coverage

Reduce interference

5..8 deg

FeederFeeder

Feeder parameter

Type Diameter 1800MHz 900MHz (mm) dB/100m dB/100

m

3/8” 10 14 10

5/8” 17 9 6

7/8” 25 6 4

1 5/8” 47 3 2

Use the short feeder whenever possible

Distributed AntennasDistributed Antennas

Leaking feeder

Cables with very high loss per length unit “distributed antenna”

often used for tunnel coverage. This kind of feeder is expensive

Optic fiber distribution system

Distribute RF signal radiate from discrete antenna points at

remote locations via (very thin) optic fiber.

50 Ohm

Propagation loss: 4 ... 40 dB/100m

coupling loss: ~ 60 dB (at 1m dist.)

RepeatersRepeaters

Repeater type

Narrow-band Repeater

Wide-band Repeater

The Repeater is used to relay signal into shadowed area

Behind hill

Into valley

Into building

Note: The Repeater needs a host cell

decoupling ~40 dB needed




3. Antenna systems



6. Link budget

DiversityDiversity

Time diversity

Coding, interleaving

Frequency diversity

Frequency hopping

Space diversity

Multiple antennas

Polarization diversity

Dual-polarized antennas

Multi-path diversity Equalizer

t

f

Benefit From DiversityBenefit From Diversity

Diversity gain depends on environment

Antenna diversity

3dB gain

More path loss acceptable in link budget

Higher coverage range

R

R(div) ~ 1,3 R A 1.7 A 70% more coverage per cell Needs, less cells in total

The above case can be satisfied only under ideal condition. That is the environment is infinitely large and flat




3. Antenna systems



6. Link budget

InterferenceInterference

Signal quality =sum of all expected signals carrier (C )sum of all unexpected signal interference (I)=

Notes: GSM specification : C / I >= 9 dB (Co-Channel)

expected signalatmosphericnoise

other signals

Effects of InterferenceEffects of Interference

Affect signal quality

Cause bit error

Repairable errors : channel coding, error correction

Irreducible errors : phase distortions

Interference situation is

Non- reciprocal : uplink <> downlink

Unsymmetrical : different situation at MS and BTS

C/I

Co-Channel C/I : 9dB

Adjacent Channel C/I : -12dB

Signal Quality in GSMSignal Quality in GSM

RX Quality RXQUAL class : 0 ... 7

RXQUAL Mean BER BER rangeclass (%) from... to0 0.14 < 0.2%1 0.28 0.2 ... 0.4 %2 0.57 0.4 ... 0.8 %3 1.13 0.8 ... 1.6 %4 2.26 1.6 ... 3.2 %5 4.53 3.2 ... 6.4 %6 9.05 6.4 ... 12.8 %7 18.1 > 12.8 %

usable signal

unusablesignal

good

acceptable

Interference sourcesInterference sources

Multi-path (long echoes)

Frequency reuse

External interference

Note : Interference has the same effect as poor coverage.

Reduce the interference as possible.

Methods for reducing InterferenceMethods for reducing Interference

Frequency planning

Suitable site location

Antenna azimuth, downtilt and height

good location

bad location


Frequency hopping

A diversity technique, frequency diversity include:

Less fading loss

De-coding gain

Interference averaging

Power control based on quality

Evaluate signal level and quality

DTX

Silent transmission in speech pauses


Adaptive antenna

According to subscriber distribution, concentrate signal energy t

o certain direction.

Adaptive channel allocation

Always assign the best available channel during call setup.

Frequency HoppingFrequency Hopping

Diversity technique

Frequency diversity can reduce fast fading effects

Useful for static or slow-moving mobiles

Cyclic base-band hopping

TRX hops cyclic between its allocated frequencies

RF hopping

Either cyclic or random hopping

Needs wideband combiner

Can use any frequency included in the MA

Power ControlPower Control

Save battery life-time

Minimize interference

GSM : 15 steps and 2 dB for each

Use power control in both uplink and downlink triggered by level or quality

time

signallevel target level

e.g. -85 dm

Power control isn’t allowedon BCCH

DTXDTX

DTX (Discontinuous transmission)

Switch transmitter off in speech pauses and silence periods, bot

h sides transmit only silence updates (SID frames) comfort

noise generated by transcoder.

VAD: voice activity detection

Transcoder is informed the use of DTX/ VAD

Battery saving and interference reducing

Battery saving and interference reducing




3. Antenna systems



6. Link budget

Link Budget CalculationLink Budget Calculation

Why we need a link budget?

Which will decide the coverage range?

The coverage range is limited by the weaker one.

Two-way communication needed

link usually limited by mobile transmitting power

Desired result: downlink = uplink

Link budget shouldbe balanced

Exercises

1. Write down the diversity techniques.

2. Write down the antenna’s main parameters.

3. Write down the method used to reduce interference.

Answer

1.The diversity techniques are time diversity, frequency diversity,

space diversity and polarization diversity.

2.The antenna’s main parameters are lobes (main lobes, side/ba

ck lobes), front-to-back ratio, half-power beam-width ,antenna do

wntilt, polarization, frequency range, antenna impedance, mecha

nical size etc..

3.The methods used to reduce interference are frequency hoppi

ng, DTX, power control based on qulality, adaptive antenna, opti

mized channel allocation.



Mobile radio link



Network Planning ProcedureNetwork Planning Procedure

1. Cellular planning principle

2. Network topology

3. Traffic estimation

4. Coverage planning

5. Frequency planning

6. Site selection

7. Transmission planning

Network Planning PrincipleNetwork Planning Principle

marketing

business plan

traffic estimate

initial dimensioning

Frequency plan

transmission plan

finaltopology

parameter plan

coverage plan

Scope of Network PlanningScope of Network Planning

Operator’s requirements

Subscriber forecasts

Coverage requirements

Quality of service

Recommended sites

Network design

Number & configuration of BSC

Antenna specifications

BSS topology

Frequency plan

Network evolution strategy

External information

Terrain data

Population data

Bandwidth available

Network performance

Gos

Margin calculations

Interference probabilities

Quality observation

Network planning Data acquisition

Site survey

Field measurement evaluation

CW design and analysis

Transmission plan

Input DataInput Data

Maps

Main city

Important road

Location of mountain range

Inhabited area

Shore line

Local knowledge

Typical architecture

Structure of city

Demographic DataDemographic Data

Statistical yearbook

Largest town and city

Population distribution

Where are the expected subscribers

Local knowledge

Population migration route

Traffic volume

Subscriber concentration area300 000 pop.

400 000 pop.

250 000 pop.

Network ConfigurationNetwork Configuration

Estimate number of BTS neededVERY rough initial estimation :

total operator’s bandwidth

planned freq. reuse rate

number of BTS needed for traffic reasons

Evaluate achievable cell coverage range=f (topography, requirements, signal levels,

environment, ...)

number of BTS needed for coverage reasons

= average number of TRX allowed per cell

Finances Marketing

Planning

Network PlanningNetwork Planning


2. Network topology




6. Site selection


Network TopologyNetwork Topology

Umbrella cell Macro cell Micro cell Pico cell

Macro Cell NetworkMacro Cell Network

Cost performance solution

Suitable for covering large area

Large cell range

High antenna position

Cell ranges 2 ..20km

Used with low traffic volume

Typically rural area

Road coverage

Normally Use omnidirectional antenna

Exception: Use beamed antenna for road coverage

2..20 km

Micro Cell NetworkMicro Cell Network

Capacity oriented network

Suitable for high traffic area

Mostly used with beamed cell

Cost performance solution

Usage of available site’s equipment

Typical application

Medium town

Suburb

Typical coverage range: 0.5 .. 2km

0,5 .. 2km

Cell coverage rangeCell coverage range

Achievable cell coverage depend on

Frequency band (450, 900, 1800 MHz)

Surroundings and environment

Link budget figure

Antenna type

Antenna direction

Minimum required signal level

Hexagons and CellsHexagons and Cells

Three cells ( three hexagons)



2. Network topology




6. Site selection


Traffic EstimationTraffic Estimation

Estimate number of subscribers

Long-term prediction

Forecast Subscribers

Expected traffic load per subscriber

Particular habits of subscribers

Busy hour conditions

Busy hour of the day

Traffic patterns

Traffic PlanningTraffic Planning

Estimation of expected traffic

Number of subscribers in area

Traffic load per subscriber

Coverage

==> traffic per sq.km

==> traffic per cell

==> number of TRX needed per BTS

Allow extra capacity for roamer and busy hour traffic

Transmission should not be the bottleneck of the system

Traffic PatternsTraffic Patterns

Traffic varies between different hours, estimated traffic must

be able to satisfy the peak loads. Busy hour traffic is typically

twice that of the average.

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22 24 hr

%

peak hour

off-peak



2. Network topology




6. Site selection


Coverage PlanningCoverage Planning

external inputs:(traffic, subs. forecast,coverage requirements...)

Initial network dimensioning TRXs, cells, sites bandwidth needed NW topology

nominal cell plansuggestions for site locations cell parameters coverage achieved

coverage prediction signal strength multi-path propagation

coverage, ok?

site acquisition

site accepted ?

real cell planfield measurements

planningcriteria fulfilled?

N

N

N

create celldata forBSC

go tofrequency planning

Y

Y

Coverage RequirementsCoverage Requirements

Rollout phases and time schedules

Coverage requirement

Agree on min. level for outdoor coverage

Loss requirement

Indoor coverage area

Mobile classes

Operator’s cell deployment strategies

Omni-cell site in rural area

Directional site in urban area

phase 1CW launch

rolloutphase 2

rolloutphase 3

Coverage PlanningCoverage Planning

Loss

Due to coverage

Due to interference

Full coverage of an area can hardly be guaranteed ! common values: 90~95%

Network planningNetwork planning


2. Network topology




6. Site selection


Frequency PlanningFrequency Planning

Why we reuse the frequency?

8 MHz = 40 channels * 8 timeslots = 320 users

==> max. 320 simultaneous calls!!!

Limited bandwidth

Interference are unavoidable

Minimize total interference in network

Use calculated propagation prediction for frequency allocation


Target

Find solution to minimize interferences in the network

Traditional method

Hexagonal cell patterns

Regular grid

Cluster sizes

Frequency reuse distance:

D = R *sqrt(3*cluster-size) R

D


Frequency planning always consider the following case

Actual situation is different.

Power control, actual traffic and distribution of subscribers.

Average frequency reuse rate is a criteria for good allocation

scheme:

practicallimit

safe, butuneconomical

physicallimit

0 10 20

Frequency ReuseFrequency Reuse

Reuse frequency as often as possible

Increase network capacity

But maybe cause some interference

Consideration for frequency reuse

Interference matrix calculation

Propagation model tuning

Minimize total interference in network

R

D

f2

f3

f4f5

f6

f7

f3

f4f5

f6

f2

f3

f4f5

f6f2

f3

f4f5

f6

f7

f2

f3

f4f5

f7

f2

f3

f4f5f2

f3

f4f5

f6

f7

Multiple Reuse RateMultiple Reuse Rate

Frequency reuse rate

measurement criteria for effectiveness of frequency plan

Co-relationship : effectiveness interferences

Interaction with coverage planning

Multiple reuse rate increase effectiveness of freq. plan

1 3 6 9 12 15 18 21

safe planning(BCCH layer)normal planning

(TCH macro layer)

tight reuse planning (tight layer)

same frequencyin every cell(spread spectrum)

Multiple reuse rateMultiple reuse rate

Capacity increase with multiple reuse ratee.g. network with 300 cells

bandwidth : 8 MHz (40 radio channels)

Single reuse (4X3)Network capacity = 40/12 * 300 = 1000 TRX

Multiple reuse:BCCH layer: reuse =14, (14 freq.)

normal TCH: reuse =10, (20 freq.)

tight TCH layer: reuse = 6, (6 freq.)

==> Network capacity = (1 +2 +1)* 300 = 1200 TRX

cap NBW

re usei

i

.



2. Network topology




6. Site selection


Site LocationSite Location

Cell performance has a close relationship with site location

Site is long-term investment

Site acquisition is a slow process

Hundreds of sites needed per network

Site is a valuable long-term asset for the operator

Bad Site LocationBad Site Location

Avoid hill-top location for site

Uncontrollable interference

Cross coverage

Bad handover behavior

wanted cellboundary

uncontrolled, stronginterferences

cross coverage areas:

Good Site LocationGood Site Location

Prefer site off the hill-top

Use hill to separate cell

Contiguous coverage area

Need only low antenna height if site are slightly elevated above

valley bottom

wanted cellboundary

Site Selection CriteriaSite Selection Criteria

Radio criteria

Good view in main beam

direction

No obstacles

Good visibility of terrain

Antenna installation situation

LOS to next microwave site

Short feeder length

Non-radio criteria

Space for equipment

Availability of leased transmission l

ine or microwave link

Power supply

Access restrictions

House owner

Rental costs

Site Acquisition ProcessSite Acquisition Process

radio planner

fixed networkplanner

measurementteams

architect

network operator

Site selectsite owner

Site InformationSite Information

Questionnaire Collect all necessary information about site

Site coordinates, height above sea level, exact address

House owner

Type of building

Building materials

Possible antenna heights

360deg photo (clearance view)

Neighborhood, surrounding environment

Drawing sketch of rooftop

Antenna installation conditions

Access possibilities (road, roof)

BTS location, approximately feeder lengths



2. Network topology




6. Site selection


Transmission PlanningTransmission Planning

A great portion of yearly network operational cost is

transmission maintenance cost.

Transmission planning is for minimizing the overall cost

Fixed part design

MSC

BSC Hub

BTS

BSS

BTS

BTS

BTS

Radio part design

BTS

BSS

BTS

BTS

BTS

Transmission ConceptTransmission Concept

Transmission media

Transmission techniques

Transmission methods

Fiber

Coaxial cable

Copper cable

Microwave radioTerrestrial/satellite

PDH SDH

PCMISDN ATM

Tra

nsm

issi

on

eq

uip

men

tHDSL

CATV

Microwave LinksMicrowave Links

Pro

Low operating costs

Easy to install

Flexible

Quick & reliable solution

High capacity transmission links, frequency range: 7~38 GHz

Normal transmission link

Needs extra frequencies

Link quality depend on weather

Not always available at ideal sites

(LOS path)

Long distance hops are problematic

Terminalstation A

Terminalstation B

Repeaterstation

Basic Transmission TopologiesBasic Transmission Topologies

POINT-TO-POINT STAR (Concentration points)

The basic criteria for choosing transmission topologies is Costs vs. Fail Safety (redundancy).

LOOPMULTIDROP CHAIN

Network topologyNetwork topology

Prefer centralized or decentralized network architecture

2 small BSC plus cheap transmission

1 large BSC plusexpensive transmission

MSC

BTS

BSC

BTS

BTS

BTS

BSC/ MSC

BTS

BTS

BTS

BTS



Mobile radio link



Advanced Network PlanningAdvanced Network Planning

1. Network evolution

2. Indoor coverage

3. Tunnel coverage

4. Parameters

Cell EvolutionCell Evolution

Umbrella Cell5-50KmEarly 80’s

Macro Cell1-5KmMid-end 80’s

Micro Cell100m-1KmMid 90’s

Pico Cell10m-100mMid-end 90’s

Macro Cell Layered Network

Layered NetworkLayered Network

High layer station

Middle layer stationMiddle layer station

Indoors stationIndoor station

Indoors station

Low layer station Low layer station Low layer stationLow layer station

Indoors station

Network Capacity evolutionNetwork Capacity evolution

Measure for network spectrum efficiency

Erl/ (MHz * sq.km)

A function of

Bandwidth

Frequency efficiency of technology

Frequency reuse

Cell size

Frq. hoppingFrq. hopping

DTXDTX

DirectedRetry

DirectedRetry

PowerControl

PowerControl

Half-ratecode

Half-ratecode

Loaddistribution

Loaddistribution

Load HOLoad HO

multiple cellcoverage

multiple cellcoverage



2. Indoor coverage

3. Tunnel coverage

4. Parameters

Why IndoorsWhy Indoors

Indoor coverage become the main competition between operators

Subscribers expect continuous coverage and better quality

Outdoor cell can’t provide sufficient indoor coverage

INDOOR SOLUTION

Good Quality!

BenefitsBenefits

Low Transmission Powers (BTS/MS)

Dedicated Indoor Solution

Good Quality

Safety

MS Battery Life-time

Office Equipment

Less Interference

Continuous Coverage

Subscriber expectation

Continuous Service

Building Penetration LossBuilding Penetration Loss

Signal level in building is estimated by using a building

penetration loss margin

Big differences between rooms with window and without

window(10~15 dB)

rear side :-18 ...-30 dB

Pref = 0 dB

Pindoor = -3 ...-15 dB

Pindoor = -7 ...-18 dB

-15 ...-25 dB no coverage

signal level increases with floor number :~1.5 dB/floor (for 1st ..10th floor)

Building Penetration LossBuilding Penetration Loss

Signal loss for penetration varies between different building

materials, e.g.: mean value

reinforced concrete wall, windows 17 dB

concrete wall, no windows 30 dB

concrete wall within building 10 dB

brick wall 9 dB

armed glass 8 dB

wood or plaster wall 6 dB

window glass 2 dB

Total building loss = median values +

superimpose standard deviations +

(lognormal) margin for higher probabilities

In-Building Path LossIn-Building Path Loss

Simple path loss model for in-building environment

Outdoor loss: Okumura‘s formula

Lout = 42,6 + 20 log( f ) + 26 .. 35 log( d )

Wall loss

Lwall = f (material; angle)

Indoor loss: linear model

For Pico-Cells

Lin = L0 + d d

building type loss application example

old house 0,7 dB/m (urban l)

commercial type 0,5 dB/m (modern offices)

open room, atrium 0,2 dB/m (museum, train station)

Lout

Lwall

Lin

Indoor Coverage SolutionsIndoor Coverage Solutions

Small BTS

Mini BTS

Repeater

Active

Passive

Optical

Antennas

Distribute antenna

Leaky cable

Signal distribution

Power splitter

Optical fiber

Indoor PlanningIndoor Planning

Example2:1.2 MHz allocation50 mErl/subscriber , GOS=2%reuse per two floor, separate frequencies within one floor:a) three floors

52.12 Erl => 842subsb) ten floors

140 Erl => 2808 subs

Example1:1.2 MHz allocation50 mErl/subscriber, GOS=2%no frequency reuse:

a) three floors

34.68 Erl=> 694 subscribersb) ten floors

34.68 Erl => 694 subscribers

Single cell approach Multi-Cell approach

t

f5

f6

f5

f1

f2

f1

f3

f4

f3f1..f6

f1..f6

f1..f6

Leaky cableLeaky cable

Coaxial cable with perforated leads

Radiating loss 10~40 dB per 100m

Coupling loss typically 55 dB (at 1m)

Produce constant field-strength along cable runs

Work at wide-band

Radiating loss become higher with high frequency

Very large bending radius

Formerly often used for tunnel coverage

Expensive

Indoor Coverage ExamplesIndoor Coverage Examples

With Repeater

Relay outdoor signal into target building

Need donor cell, add coverage but not capacity

With indoor BTS and distributed antenna

Heavy loss bring by power splitting and cable

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

50m

50m

1:1

1:1:1

1:1

4th floor

3rd floor

2nd floor

1st floor

ground floor

Outdoor AntennaGain: 18 dBi

Indoor AntennaGain: 9dBi

Target Indoor Coverage Building

7/8'' Cable Loss: 4dB / 50mCable length : 25m

-50 dBm

4th Floor

3rd Floor

1st Floor

Ground Floor

2nd Floor

RepeaterRepeater

Types of Repeater

According to operating frequency

Wide-band Repeater

Narrow-band Repeater

According to working method

Passive Repeater

Needs strong external signal, useful only with

very short cables and seldom used

Active Repeater

Amplify and re-transmits all received signals

needsdecoupling > amplification

RepeaterRepeater

Application examples

Coverage for low traffic area

Remote valley

Tunnel

Underground coverage

The Bulb PrinciplesThe Bulb Principles

Several smaller sites provide more indoor coverage area than a single large site

... is better than ...

Newspaper PrinciplesNewspaper Principles

The newspaper-principle

Indoor coverage may be expected in locations where there is no enough daylight to read a newspaper comfortably



2. Indoor coverage

3. Tunnel coverage

4. Parameters

Wave Propagation in TunnelsWave Propagation in Tunnels

Ideal antenna position: center of cross-section

Distance to walls: min. 2λ

Tunnel cross-section shape unimportant, if λ > 10

Time dispersion decreases with distance

Install antenna 50~100m before tunnel entrance

Good signal coupling between successive tunnels

Tunnels are very suitable environment for radio wave propagation

Tunnels are very suitable environment for radio wave propagation

Tunnel Cross-SectionTunnel Cross-Section

Filling factor determines propagation condition

Typical range for filling factors

Road tunnels: 10%

Metro: 60~90%

filling factor =----------



2. Indoor coverage

3. Tunnel coverage

4. Parameters

BSS ParametersBSS Parameters

BSS Relevant Parameter for Network Planning

Frequency allocation plan

Logical radio configuration

Transmitting power

Definition of neighboring cells

Definition of location areas

Handover parameters

Power control parameters

Cell selection parameters

Radio link time-out counter

Topology of BSC- BTS network

Handover TypesHandover Types

Intra-cell same cell but different carrier or timeslot

Inter-cell different cells (normal case)

Inter-BSC different BSC

Inter-MSC different MSC

Inter-PLMN (technically feasible, not supported)

Intra-cell

Inte-rcell

inter-BSC

Handover CriteriaHandover Criteria

1. Interference, UL and DL

2. Bad C/I ratio

3. Uplink Quality

4. Downlink Quality

5. Uplink Level

6. Downlink Level

7. Distance

8. Rapid Signal Drop

9. MS Speed

10. Power Budget

11. Good C/I ratio

12. PC: Lower quality/level

thresholds (DL/UL)

13. PC: Upper quality/level

thresholds (DL/UL)

Location Area DesignLocation Area Design

Location update affects all mobiles in network

Location update in idle mode

Location update after call completion

Location update brings extra burden to the network

Good location area design should avoid ping-pong

location update

Location area 1

Location area 2major road

Paging VS Location update TrafficPaging VS Location update Traffic

PagingLocation update

# of cells in Loc. area

signalingtraffic

optimum numberof cells in Loc. area

function of user density,cell size, call arrival rate ...function of

user mobility

minimize signaling traffic

optimum varies with network evolution

Exercises

1. Write down the network evolution process.

2. Write down solution and equipment for indoor coverage.

3. Write down the types of handover.

Answer

1.The network evolution process is: Umbrella cell-> Macro cell -

>Micro cell->Picro cell

2. The solution and equipment for indoor coverage are: M

ini BTS, Repeater, antennas( distribute antenna, leaky ca

ble), signal distribution( power splitter, optical fiber).

3.The handover types are: Inter BSC, Intra BSC, Intra cell, Inter

cell, Inter MSC and Intra MSC.

Documents

OMF000502 Network Planning Principle ISSUE1.3